1. Field of the Invention
The present invention relates to a novel image forming layer, and more precisely it relates to an image forming layer enabling to obtain a negative image with high sensitivity from original image by light exposure.
2. Prior Arts
Recently, the development process in the formation of printing plates or resists has been carried out by the alkali development using an aqueous alkaline solution instead of the former development using a developer mainly consisting of an organic solvent from the viewpoints of the environmental safety and sanitary. Accordingly, it has been required to use a light-sensitive layer suitable for the alkali development, and various binder polymers or resins containing carboxyl groups are utilized. However, such binder compounds have serious drawbacks that when they are used in printing plates or resists the image portions obtained after the light exposure and the development tend to swell with the alkaline developer due to the carboxylic acid remained therein to unacceptable reduce the coating strength and the adhesion to the substrate of the image portions.
In order to eliminate those drawbacks, it was proposed to eliminate the carboxylic acid by decarbonation of the carboxylic acid by means of light exposure as disclosed in JP (KOKAI) No. 64-32255. However, this method enables to obtain only low sensitivity, and the image portions obtained with a weak light exposure in this method show poor scratch resistance during the development process since a lot of carboxylic acid remains in the image portions when the light exposure is rather weak.